An inflatable cushion restraint disposed within a supporting structure such as a dash panel or other fixed portion of an automobile body in opposing relation to a seat in the vehicle plays an important role in protecting the passengers in the vehicle from injury due to collision against the automobile body. Typically, the inflatable cushion is inflated rapidly by the pressure of a reaction gas released from an inflator during a collision. This gas generation takes place when a gas generating agent in the inflator induces a chemical reaction by a collision signal from a collision detecting sensor when the deceleration of the vehicle exceeds a predetermined set level. The gas which is generated by the generator is thereafter conveyed to the inflatable cushion which extends outwardly as it fills with gas to create a protective barrier between the vehicle occupant and the dash panel or other portion of the vehicle against which the occupant might otherwise be thrown.
As will be appreciated, it is important to provide efficient and effective ways to mass produce suitable inflatable cushions. Heretofore, inflatable cushions which are commonly referred to as air bags have typically been formed from numerous pieces of fabric cut into different shapes and fastened together by sewing to form the desired configuration. An opening formed in one of the pieces of fabric functions as a gas inlet opening for the cushion. Additional fabric may also be attached to the cushion in the proximity of the gas inlet opening to provide transmission means for the inflating medium. One such inflatable cushion is disclosed in U.S. Pat. No. 5,090,729 to Watanabe, the teachings of which are incorporated herein by reference.
It is to be understood that pre-cutting a number of odd shaped pieces and thereafter sewing together these pieces to form a desired structure may require a rather complex operation and can give rise to a significant amount of wasted fabric. In the patent literature there has been some recognition that simplified structures may be advantageous in both minimizing operational steps as well as in maximizing available materials.
U.S. Pat. No. 4,944,529 to Backhaus (incorporated by reference) discloses an inflatable cushion having a substantially quadrilateral configuration which is formed from no more than two flat blanks cut from web material.
U.S. Pat. No. 5,087,071 to Wallner (incorporated by reference) discloses an inflatable cushion formed from a length of fabric folded at predetermined locations to form a central portion and two end portions. The partially overlapping end portions and aligned edges of the central and end portions are joined together to form an inflatable bag adapted to form a predetermined configuration when inflated with gas.
German Patent 24 39 222 published Feb. 26, 1976 illustrates a cushion made from one piece of material cut in a special way with a pattern of V-shaped slots brought together at sealing seams to form the cushion. The shape of the pattern and the setting of the material is chosen so that no seam is at a 45.degree. angle to the warp or to the weft of the material.
Japanese Published Application 5-77342 published Mar. 30, 1993 illustrates an inflatable cushion formed by folding a completely square piece of material such that the four corners are folded back to a depth longer than half of one side of the square after which the resulting overlapping portions are bonded together.
As will be appreciated, prior designs tend to either result in relatively poor material utilization by incorporating complex initial geometries, or require fairly complex sewing operations to form an enclosed cushion. The present invention provides for the use of relatively simple starting geometries for the fabric components in combination with easily mechanized folding operations and a single perimeter joining operation to form an enclosed cushion having sufficient depth to provide a degree of protection to a vehicle occupant while nonetheless permitting the cushion to remain flat during assembly. Accordingly, the present invention represents a useful advancement over the present art.